(RA-1) T. H. James, "The Theory of the Photographic Process," 4th Edition, New York (1977). PA0 (RA-2) K. R. Hollister and E. J. Perry, U.S. Pat. No. 3,813,251 (1974), describes the preparation of AgX grains using thioether group containing acrylate copolymers; M. J. Fitzgerald, "Synthetic Silver Halide Emulsion Binders," U.S. Pat. No. 3,816,129 (1974). PA0 (RA-3) P. Bagchi, "Gelatin-Grafted-Polymer Particles," U.S. Pat. No. 4,920,004 (1990). PA0 (RA-4) P. Bagchi, M. D. Sterman, and H. M. Low, "Photographic Element Having Polymer Particles Covalently Bonded to Gelatin," U.S. Pat. No. 4,855,219 (1989); K. M. O'Conner, R. P. Szajewski, and P. Bagchi, "Control of Pressure-Fog with Gelatin-Grafted and Case-Hardened Gelatin-Grafted Soft Polymer Particles," U.S. Pat. No. 5,066,572 (1991); P. Bagchi, R. F. Reithal, T. J. Chen, and S. Evans, "Photoresist Dichromate Composition Containing Gelatin Coated Particles," U.S. Pat. No. 5,055,379 (1991). PA0 (RA-5) P. Bagchi, "Theory of Stabilization of Spherical Colloidal Particles by Nonionic Polymers," J. Colloid and Interface Science 47, 100 (1974). PA0 (RA-6) P. Bagchi and W. L. Gardner, "Use of Gelatin-Grafted and Case-Hardened Gelatin-Grafted Polymer Particles for Relief from Pressure Sensitivity of Photographic Products," U.S. Pat. No. 5,026,632 (1991). PA0 (RA-7) W. Schmidt, "Photographic Material," U.S. Pat. No. 4,973,547 (1990); S. A. King and J. E. Maskasky, "Modified Peptizer Twinned Grain Silver Halide Emulsions and Process for Their Preparation," U.S. Pat. No. 4,942,120 (1990). PA0 (RA-8) T. J. Chen, Describes loading of photographically useful compounds into latex particles for delivery in photographic coating, U.S. Pat. No. 4,199,363 (1980). PA0 (RA-9) P. Bagchi, S. J. Sargeant, J. T. Beck, and B. Thomas, "Polymer Co-Precipitated Coupler Dispersion," U.S. Pat. No. 5,091,296 (1992). PA0 (RA-10) H. Bains, E. P. Davey, and E. T. Teal, U.S. Pat. No. 2,618,553 (1946) describes a mixed-packet color photographic process. PA0 (RA-11) P. Bagchi, B. V. Gray, and S. M. Bisnbaum, "Preparation of Model Polyvinyltoluene Latexes and Characterization of Their Surface Charge by Titration and Electrophoresis," J. Colloid and Interface Science 69, 502 (1979). PA0 (RA-12) H. G. Curme and C. C. Natale, J. Phys. Chem. 63, 3009 (1964). PA0 (RA-13) K. Sato, S. Ohno, and S. Yamada, "Silver Halide Photographic Material," U.S. Pat. No. 4,877,720 (1989). PA0 (RA-14) N. Sujimoto, T. Kojima, and Y. Mukunoki, "Silver Halide Photographic Light-Sensitive Material," U.S. Pat. No. 4,464,462 (1984). PA0 (RA-15) A. G. Van Paesschen, "Polymerization of Monomeric Couplers," U.S. Pat. No. 4,080,211 (1978). PA0 (RA-16) J. J. Chechak and S. S. Firke, "Resin Salt of Couplers in Mixed-Packet Photographic Emulsions," U.S. Pat. No. 2,698,796 (1955). PA0 (RA-17) L. Godowsky and L. M. Minsk, "Mixed-Packet Photographic Emulsions Using Resin Couplers," U.S. Pat. No. 2,698,797 (1955). PA0 (RA-18) J. H. Van Campen and J. W. Gates, "Modifiers for Photographic Packet Emulsions," U.S. Pat. No. 2,763,552 (1956). PA0 (RA-19) V. Tulagin and R. D. Jackson, "Mixed-Packet Photographic Emulsions," U.S. Pat. No. 2,965,484 (1960). PA0 (RA-20) L. Godowsky, "Mixed-Packet Photographic Emulsions," U.S. Pat. No. 2,698,794 (1955). PA0 (RA-21) K. W. Schranz, "Photographic Recording Material," U.S. Pat. No. 4,865,940 (1989). PA0 (RA-22) A. G. E. Mignot, "Silver Halide Precipitation Process with Deletion of Materials," U.S. Pat. No. 4,334,012 (1982). PA0 (RA-23) S. Urabe, "Process for Preparing Silver Halide Grains," U.S. Pat. No. 4,879,208 (1989). PA0 (RA-24) J. C. Cohen, W. L. Gardner, and A. H. Herz, Adv. Chem. Ser. 45, 198 (1973). PA0 (RA-25) A. Holland and A. Fieinerman, J. Appl. Photogr. Eng. 8, 165 (1982). PA0 (RA-26) Anonymous, "Photographic Silver Halide Emulsions, Preparations, Addenda, Processing, and Systems," Research Disclosure 308, p. 993, December 1989.
Traditionally, various types of gelatin have been used for the precipitation of photographic silver halide emulsions. Various synthetic water soluble polymers have also been found to be useful in the precipitation of photographic silver halide emulsions (RA-2). Hollister and Perry describe a variety of such water soluble polymers that contain pendent thioether groups, that are particularly suitable for the precipitation of Ag-halide photographic emulsions (RA-2). Gelatin-grafted-polymer particles have been described recently (RA-3). Gelatin-grafted-polymer particles are polymer particles with a monomolecular layer of gelatin chemically bonded to the polymer particles. Such particles have been particularly useful for use as matting agents, and agent for the relief of pressure sensitivity of photographic layers, and in the fabrication of color filter arrays (RA-4). In any colloidal peptization by steric stabilization, the most important parameter that governs the stability of a dispersion or an emulsion is the thickness of the protective stabilizer layer (RA-5) around the particle. A thicker adsorption layer causes a larger distance between the particles, stabilizing them from coagulation due to the decreased van der Waals attraction between the particles.
Many types of synthetic peptizers have been used in the preparation of AgX crystals. The most useful synthetic compositions have been those that contain thioether moieties (U.S. Pat. No. 3,813,251). Because of the necessity of higher and higher speeds of photographic emulsions (particularly in tabular grain emulsions) the silver halide crystals used in photographic systems today are getting bigger and bigger. Therefore, for their colloidal protection thicker protective adsorption layers are desirable. Various derivatized gelatins, meaning gelatin chemically bonded to organic molecules and water soluble polymeric molecules, have also been used to prepare photographic emulsions (RA-7).
Gelatin being a polyelectrolyte with an isoelectric pH (IEP), the adsorption layer thickness of the gelatin on a particle surface depends on the pH and the ionic strength (RA-4 and RA-5). Under low electrolyte conditions, which is the most favorable condition for colloidal stability, the thickness of the gelatin layer may vary anywhere from 10 to 60 nm. Under silver halide precipitation conditions, where the electrolyte concentration is very high, the smaller value is expected as the adsorbed polyelectrolyte would have the most compact structure under such conditions, which is detrimental to colloidal stability. FIG. 1 shows a pictorial view of a gelatin-grafted-polymer particle, where the bonded gelatin layer will also have the kind of dimension as described above. A further description of gel-g-latex particles can be found in (RA-6). It is also disclosed in (RA-3) and (RA-4) that the inner core polymer particles of a gel-g-polymer particle can be prepared with a diameter anywhere between 10 to 10.sup.6 nm.